The present invention relates to an information sharing system, a computer, and an information sharing method.
Some in-vehicle systems installed in a vehicle need to share confidential information with a server in order to securely communicate with the server. The in-vehicle system and the server use the shared confidential information as a key, and securely communicate with each other via cryptography.
In a case where confidential information is not shared between the in-vehicle system and the server in advance, the confidential information needs to be shared between the in-vehicle system and the server at first. There is a known technology to make it possible to share confidential information between a server and an in-vehicle system that do not have shared confidential information in advance (see Patent Document 1, for example).
According to Patent Document 1, a key distributing device and a key receiving device are each given an asymmetric key in advance, and the key distributing device securely distributes a new key to the key receiving device using this asymmetric key. The asymmetric key is a pair of a private key and public key. If the key distributing device is a server, and the key receiving device is an automobile, the key, which is the confidential information, can be shared between the server and the automobile, which do not have shared information to begin with, using the technology disclosed in WO 00/69113 A1.